﻿using System;
using System.Reflection;
using System.Xml;

namespace KubeUI;

public static class ModelCacheExtensions
{
    /// <summary>
    /// Provides the documentation comments for a specific method
    /// </summary>
    /// <param name="methodInfo">The MethodInfo (reflection data ) of the member to find documentation for</param>
    /// <returns>The XML fragment describing the method</returns>
    public static XmlElement GetDocumentation(this MethodInfo methodInfo)
    {
        // Calculate the parameter string as this is in the member name in the XML
        var parametersString = "";
        foreach (var parameterInfo in methodInfo.GetParameters())
        {
            if (parametersString.Length > 0)
            {
                parametersString += ",";
            }

            parametersString += parameterInfo.ParameterType.FullName;
        }

        //AL: 15.04.2008 ==> BUG-FIX remove “()” if parametersString is empty
        if (parametersString.Length > 0)
            return XmlFromName(methodInfo.DeclaringType, 'M', methodInfo.Name + "(" + parametersString + ")");
        else
            return XmlFromName(methodInfo.DeclaringType, 'M', methodInfo.Name);
    }

    /// <summary>
    /// Provides the documentation comments for a specific member
    /// </summary>
    /// <param name="memberInfo">The MemberInfo (reflection data) or the member to find documentation for</param>
    /// <returns>The XML fragment describing the member</returns>
    public static XmlElement GetDocumentation(this MemberInfo memberInfo)
    {
        // First character [0] of member type is prefix character in the name in the XML
        return XmlFromName(memberInfo.DeclaringType, memberInfo.MemberType.ToString()[0], memberInfo.Name);
    }

    /// <summary>
    /// Provides the documentation comments for a specific type
    /// </summary>
    /// <param name="type">Type to find the documentation for</param>
    /// <returns>The XML fragment that describes the type</returns>
    public static XmlElement GetDocumentation(this Type type)
    {
        // Prefix in type names is T
        return XmlFromName(type, 'T', "");
    }

    /// <summary>
    /// Returns the Xml documentation summary comment for this member
    /// </summary>
    /// <param name="memberInfo"></param>
    /// <returns></returns>
    public static string GetSummary(this MemberInfo memberInfo)
    {
        var element = memberInfo.GetDocumentation();
        if (element == null) return "";
        var summaryElm = element?.SelectSingleNode("summary");
        if (summaryElm == null) return "";
        return summaryElm.InnerText.Trim();
    }

    /// <summary>
    /// Gets the summary portion of a type's documenation or returns an empty string if not available
    /// </summary>
    /// <param name="type"></param>
    /// <returns></returns>
    public static string GetSummary(this Type type)
    {
        var element = type.GetDocumentation();
        if (element == null) return "";
        var summaryElm = element?.SelectSingleNode("summary");
        if (summaryElm == null) return "";
        return summaryElm.InnerText.Trim();
    }

    /// <summary>
    /// Obtains the XML Element that describes a reflection element by searching the
    /// members for a member that has a name that describes the element.
    /// </summary>
    /// <param name="type">The type or parent type, used to fetch the assembly</param>
    /// <param name="prefix">The prefix as seen in the name attribute in the documentation XML</param>
    /// <param name="name">Where relevant, the full name qualifier for the element</param>
    /// <returns>The member that has a name that describes the specified reflection element</returns>
    private static XmlElement XmlFromName(this Type type, char prefix, string name)
    {
        string fullName;

        if (string.IsNullOrEmpty(name))
            fullName = prefix + ":" + type.FullName;
        else
            fullName = prefix + ":" + type.FullName + "." + name;

        var xmlDocument = XmlFromAssembly(type.Assembly);

        if (xmlDocument == null)
        {
            return null;
        }

        var matchedElement = xmlDocument["doc"]["members"].SelectSingleNode("member[@name='" + fullName + "']") as XmlElement;

        return matchedElement;
    }

    /// <summary>
    /// Obtains the documentation file for the specified assembly
    /// </summary>
    /// <param name="assembly">The assembly to find the XML document for</param>
    /// <returns>The XML document</returns>
    /// <remarks>This version uses a cache to preserve the assemblies, so that
    /// the XML file is not loaded and parsed on every single lookup</remarks>
    public static XmlDocument XmlFromAssembly(this Assembly assembly)
    {
        //if (ModelCache.Cache.TryGetValue(assembly, out var value))
        //{
        //    return value;
        //}

        return null;
    }
}
